System for adjusting operating and release sensitivities of magnetically biased relay armatures



Nov. 18, 19-69 J. B. cAsEY 3,479,584

SYSTEM FOR ADJUSTING OPERATING AND RELEASE SENSITIVITIES 0F MAGNETICALLY BIASED RELAY ARMATURES Filed Sept. 20, 1966 4 Sheets-Sheet 1 29 f BIAS MAG. SATURATION UNIT /6 17 A A A A 35 37 /2/-\. L /3 3 DEMAG. 5/1 DE J 34/ UNIT I4 um? 0 A /6" 2/ 27 i 23- 22 v SEQUENTIAL con. cuRRENT PULSE '26 WAVEFORM GENERATOR 32 B/- GENERATOR T |.............T....T 8

1- DETECTOR UNIT LOGIC UNIT FIG.

INVENTOR J 5. CA SE V 8, 1969 J. a. CASEY SYSTEM FOR ADJUSTING OPERATING AND RELEASE SENSITIVITIES OF MAGNETICALLY BIASED RELAY ARMATURES Fi led Sept. 20. 1966 4 Sheets-Sheet mmPZDOU ENSITIVITIES 4 Sheets-Sheet 5 mP U 102 J. B; CASEY OF MAGNETICALLY BIASED RELAY ARMATURES SYSTEM FOR ADJUSTING OPERATING AND RELEASE 5 Nov. 18, 1969' Filed Sept. 20, 1966 Nov. 18, 1969 Filed Sept. 20, 1966 J. B. CASEY SYSTEM FOR ADJUSTING OPERATING AND RELEASE SENSITIVITIES 0F MAGNETICALLY BIASED RELAY ARMATURES 4 Sheets-Sheet 4 NC I 2 63 NOR 66 I GATE F/F Z F NOR T GATE 7G 7c9 6 w 4 NOR F/F 89 GATE 87 NO DETECT o RESET MODULE F/G. 5 t! Lu ld I u I 6 I z i Q i Z V E I 3 b I g f o l 9 I E? I ICOARSE I I 1 1 l 1 I I i I '2 l I 1 (I C! I D U a e 1 a 0 |/60 2/60 3/60 4/60 5/60 6/60 7/60 6/60 TIME IN SECONDS P1 L J L f P2 l L J P3 l 1 :5 P4 L W *3 P5 L J 9 P6 1 j P7 L] P8 U TIME IN SECONDS FIG. 7

United States Patent O 3,479,584 SYSTEM FOR ADJUSTING OPERATING AND RELEASE SENSITIVITIES F MAGNET- ICALLY BIASED RELAY ARMATURES John B. Casey, Lees Summit, Mo., assignor to Western Electric Company, Incorporated, New York, N.Y., a corporation of New York Filed Sept. 20, 1966, Ser. No. 580,771 Int. Cl. G01r 31/02; G01c 25/00; H01f 13/00 US. Cl. 324-28 3 Claims ABSTRACT OF THE DISCLOSURE A relay armature biased by first and second bias magnets is adjusted by applying a series of four discrete force levels with a current step waveform generator in conjunction with a coil encircling the relay armature. A detector unit samples the state of the armature by sensing electrical continuity between the armature and a normally opened and normally closed contact. A bias applied to the armature is altered by selectively demagnetizing the bias magnets using exponentially decaying sinusoidal pulses.

This invention relates to a system for adjusting mechanical hysteresis characteristics of adjustably biased armatures and more particularly to a system for adjusting operate and release sensitivities of magnetically biased relay armatures.

In the manufacture of the relays, the force required to shift or operate a relay armature from a first position to a second position and the force required to return or release the relay armature to the first position is normally adjusted by a mechanical bending or a physical moving of the relay structure. This bending or moving requires physical access to the relay structure. A relay, in which a magnetically operable .armature is sealed in a container before adjustment, may include a pair of permanent magnets to provide mechanical biasing to the armature for setting the forces required to operate and release the armature. The magnetic field strength of these magnets can be adjusted, thereby adjusting the mechanical bias without requiring physical access to the relay structure. One such relay is described in United States Patent 2,609,464, issued Sept. 2, 1952, to J. T. L. Brown et al. entitled Relay.

Various systems have been devised to adjust these bias magnets so that the relay armature will shift back and forth between two positions upon application of desired force levels. One system includes saturating both magnets and then alternately demagnetizing the magnets until the armature will operate and release upon application of the desired force levels. It is necessary to make alternate adjustments because the two magnets interact so that the magnetic field strength of each magnet affects both the operate and release forces required. This system will adjust relays susceptible of adjustment, but will not reject other defective relays incapable of proper adjustment. For instance, relays that have nonoperate and/or hold requirements in addition to operate and release requirements.

Another system for adjusting the bias magnets in a relay includes applying a continuously varying increasing force to the relay armature until the armature operates and then applying a continuously varying, decreasing force to the relay armature until the relay armature releases. A line representing the force execution applied to the relay armature is displayed on an oscilloscope provided with markings indicating the desired operate and release forces. An operator manipulates a pair of manual controls provided to adjust the magnetic field strength of ice each bias magnet until the force execution displayed on the oscilloscope coincides with the desired operate and release forces. The bias magnets may be adjusted in a nonsystematic way so that an operator may not be able to find the proper combination of settings for the manual controls because the interaction of the two magnetic fields of the two bias magnets gives rise to an infinite number of possible combinations of settings of the manual controls of which only one combination is correct. It has been found that a skilled perator using this system will reject relays as unadjustable which could be adjusted by systematic demagnetization.

Therefore, it is an object of this invention to provide a new and improved system for adjusting mechanical hysteresis characteristics of adjustably biased armatures.

It is a further object of this invention to provide a system for adjusting operate and release sensitivities of magnetically biased relay armatures which will adjust relays susceptible of adjustment and reject relays incapable of adjustment.

It is another object of this invention to provide a system for adjusting operate and release sensitivities of magnetically biased relay armatures which adjusts the magnetic bias in a systematic way so that all relays susceptible of adjustment are adjusted thereby.

With these and other objects in view, the present invention contemplates a system for adjusting the force required to shift an armature, having an adjustable bias force applied thereto, from a first position to a second position and the force required to return the armature to the first position wherein a sequential pulse generator sequentially and repetitively generates a series of timing pulses to synchronize the operation of an armature adjusting set through a series of adjusting sequences. An armature force applying device, in response to a signal generated by the sequential pulse generator, impresses a series of discrete force levels to the armature. At the completion of the application of each force level in the series, the sequential pulse generator renders a detector unit effective to sample the state of the armature and store the information thus obtained. Upon completion of the application of the entire series of force levels, a logic unit is rendered effective to provide an output responsive to the sequentially obtained information stored in the detector unit. The output provided by the logic unit will either (1) initiate alteration of the bias applied to the armature, (2) indicate an unadjustable armature, or (3) indicate an adjusted armature.

In one embodiment of the invention, a relay armature biased by first and second bias magnets is adjusted by applying the series of discrete force levels with a current step waveform generator in conjunction with a coil encircling the relay armature. The detector unit samples the state of the armature by sensing electrical continuity between thearmature and a normally opened and normally closed contact. The bias applied to the armature is altered by selectively demagnetizing the bias magnets.

Other objects and advantages of the invention will be apparent from the following detailed description when considered in conjunction with the drawings, wherein:

FIG. 1 shows a block diagram of a system embodying the principles of the invention;

FIGS. 2 and 3, taken together, show in detailed block diagram form a relay to be adjusted and a relay adjusting set embodying the principles of this invention;

FIG. 4 shows how FIGS. 2 and 3 are combined;

FIG. 5 is a detailed block diagram of the detector modules used in the relay adjusting seat;

FIG. 6 is a graph showing a relay coil current waveform as a function of time of a relay being adjusted according to the principles of this invention; and

FIG. 7 is a graphic representation of timing pulses which coordinate a system of the invention.

RELAY TO BE ADJUSTED Referring now to FIG. 1, there is shown in schematic form a cutaway view of a relay 10 representing one of a class of devices which may be adjusted according to the system of this invention. It is to be understood that any adjustably biased armature including certain relays and pressure differential valves can be adjusted according to the system of the present invention. The relay 10 includes a magnetically operable conductive armature 11 in electrical engagement with a normally closed contact 12 and a normally opened contact 13 spaced from the normally closed contact 12. A force applied to the armature 11 will move or switch the armature 11 into electrical engagement with the normally opened contact 13. The armature 11 switches or moves back into electrical engagement with the normally closed contact 12 upon reduction of the force or upon application of a force in an opposite direction. The armature 11 and the contacts 12 and 13 are all sealed in an evacuated glass envelope 14. For purpose of this specification, the term to operate when applied to the relay 10 shall mean switching the armature 11 from the normally closed contact 12 to the normally opened contact 13 and the term to release when applied to the relay 10 shall mean switching the armature 11 from the normally opened contact 13 to the normally closed contact 12, The relay 10 shall be considered to be in an operated state when the armature 11 is in contact with the normally opened contact 13 and shall be considered to be in a released state when the armature 11 is in contact with the normally closed contact 12.

A pair of low hysteresis permanent bias magnets 16 and 17 are mounted on opposite sides of the glass envelope 14 for producing magnetic fields which alter the forces required to operate and release the magnetically operable armature 11 therein. The strength of the magnetic field produced by the magnet 16 will predominantly affect the force required to operate the armature 11, but will also affect the force required to release the armature 11 as will the strength of the magnetic field produced by magnet 17 predominantly affect the force required to release the armature 11 but will also affect the force required to operate the armature 11.

A coil 18 is provided encircling the glass envelope 14 to magnetically apply operate and release forces to the armature 11. Alternately an electrostatic force could be used to operate and release the armature 11. In a pressure differential valve, forces would be applied by fluid pressures acting on opposite faces of an armature therein.

The armature 11, a normally closed contact 12, a normally opened contact 13, the magnets 16 and 17, and the coil 18 are all enclosed in a casing 19 having an insulating base portion 21 with five electrically conducting pins 22, 23, 24, 26, and 27 extending therethrough. Opposite ends of the coil 18 are electrically connected to the pins 22 and 27. Normally closed contact 12 and normally opened contact 13 are electrically connected to pins 23 and 26, respectively.

BIAS MAGNET SATURATION AND ADJUSTING SEQUENCE FIG. 1 shows a block diagram of a relay adjusting set embodying the principles of this invention. The relay adjusting set includes the following major components, a sequential pulse generator or time base generator 28, a bias magnet saturation unit 29, a coil current waveform generator 31, an armature position or relay state detector unit 32, a logic unit 33, and two bias magnet demagnetization units 34 and 36.

The sequential pulse generator 28 sequentially and repetitively generates a series of eight timing pulses P1 through P8 as seen in FIG. 6, each appearing at a terminal T1 through T8, respectively. A sequential pulse generator may include (1) a pulse source and a ring counter, (2) a stepping switch, or (3) a pulse generator, a binary counter and a decoder. To insure proper operation of the relay adjusting set, the time duration of each pulse P1 through P8 should be greater than the switching time of the relay 10. In this instance, the time duration of each pulse P1 through P8 is one sixtieth of a second which is considerably greater than the switching time of the relay so that a standard sixty cycle line voltage may be used to step the sequential pulse generator 28. The pulses P1 through P8 generated by the sequential pulse generator 28 activate associated relays and logic circuits to first saturate the bias magnets 16 and 17 and then to synchronize the operation of the relay adjusting set through a series of adjusting sequences.

In response to a signal generated during the first series of pulses P1 through P8 from the sequential pulse generator 28, the bias magnet saturation unit 29 energizes a pair of electromagnets 37 and 38 to fully magnetize or saturate the bias magnets 16 and 17. The operation of the bias magnet saturation unit 29 is then disabled so that the degrees of magnetization of the bias magnets 16 and 17 are not altered thereby during or between the adjusting sequences.

After the saturation of the magnets 16 and 17 has been completed and the bias magnet saturation unit has been disabled, the first adjusting sequence begins when the coil current waveform generator 31, in response to signals generated by the sequential pulse generator 28, impresses a current step waveform, shown in FIG. 6, through the coil 18. At the completion of each current step in the current step Waveform, the sequential pulse generator 28 renders the detector unit 32 elfective to sample the state of the relay 10 and store the information thus obtained. Upon completion of the entire step current waveform, the logic unit 33 is rendered effective by the detector unit 32 to provide an output responsive to the sequentially obtained information stored in the detector unit 32. The output provided by the logic unit 33 will either: (1) activate one of the demagnetization units 34 or 36 and light an associated light 39 or 41. Actuation of the demagnetization unit 34 will energize the electromagnet 37 to partially demagnetize the operate bias magnet 16 as will actuation of the demagnetization unit 36 energize the electromagnet 38 to partially demagnetize the release bias magnet 17; (2) indicate by lighting a lamp 42 an unadjustable relay; or (3) indicate by lighting a lamp 43 an adjusted relay. If an acceptable relay is indicated, the coil current waveform generator 31 and the two bias magnet demagnetization units 34 and 36 are switched by a signal generated in the logic unit 33 from a coarse to a fine adjusting condition.

Upon completion of the first adjusting sequence, the pulse generator 28 recycles to initiate a second adjusting sequence. The pulse P1 appearing on terminal-.Tl of the sequential pulse generator 28 during the second adjusting sequence resets the detector unit 32 and the logic unit 33. The second adjusting sequence begins when the coil current waveform generator 31, in response to the signal generated by the sequential pulse generator 28, impresses the current step waveform through the coil. During each succeeding adjusting sequence, the pulse P1 resets the detector unit 32 and the logic unit 33. The bias magnet saturation unit 29 remains disabled until manually reset.

DETAILED DESCRIPTION Referring to FIGS. 2 and 3, taken together as shown in FIG. 4, there is shown the relay adjusting set including OR gates, AND gates, NOR gates, and NAND gates. The OR gates are characterized as providing a +V output when any of the inputs are brought to +V and a ground level output when all the inputs are grounded. The AND gates are characterized as providing a +V output when all of the inputs are brought to +V and a ground level output when any of the inputs are grounded. The NOR gates are characterized as providing a +V output when all the inputs are grounded and a ground level output if one of the inputs is at a -|-V level. The NAND gates are characterized as providing a ground level output when a +V level is provided at all of the inputs and a +V output when any input is grounded. It is to be understood that the use of positive or negative logic is merely a matter of choice.

With the relay connected in the relay adjusting set as shown, the first series of pulses P1 through P8, as seen in FIG. 6 are generated when a switch 44 is closed, applying a voltage V to the sequential pulse generator 28. Each pulse P1 through P8 is one sixtieth of a second long so that the leading edge of each succeeding pulse occurs one-sixtieth of a second after the leading edge of the preceding pulse. A series of pulses P1 through P8 is generated every eight-sixtieths of a second so that the leading edge of a pulse P1 occurs one-sixtieth of a second after the leading edge of a pulse P8 from the preceding series.

Referring again to FIGS. 2 and 3, the first series of pulses generated by the sequential pulse generator 28 elfectuates saturation of the bias magnets 16 and 17. Pulses P4 through P7 apply a +V signal across a relay 46, through an AND gate 47 and a normally closed contact 48a of a relay 48. The energization of the relay 46 switches each of the contacts 46a and 46b from a normally closed stae, as shown in FIG. 2, to a normally opened state. A source of A.C. voltage 49 is applied through a transformer 51 to a pair of diodes 52 and 53. The A.C. voltage from the source 49 is rectified by the diodes 52 and 53 and the resulting half sinusoids of voltage are applied across the electromagnets 37 and 38 through the now closed paths of contacts 46a and 46b. The fields thus produced surrounding the electromagnets 37 and =38 saturate the bias magnets 16 and 17 in the relay 10. Other waveforms, such as a square wave or direct current pulse, are equally suitable for driving the electromagnets 37 and 38 to saturate the bias magnets 16 and 17 The A.C. voltage source 49, transformer 51, the diodes 52 and 53, and the relay 46 serve as the bias magnet saturation unit 29.

The pulse P8 in the first series of pulses is applied from terminal T8 to operate a flip-flop 54 and thereby energize relay 48 to open the normally closed contact 48a. The opening of normally closed contact 48a disconnects the relay 46 from the AND gate 47 so that the pulses P4 through P7, occurring in the succeeding series of pulses, cannot energize the relay 46 to initiate saturation of the bias magnets 16 and 17 until the flip-flop 54 is reset.

The second and each succeeding series of pulses P1 through P8 coordinate the relay adjusting set through a series of adjusting sequences. In the adjusting sequences, pulses P1 through P4 sequentially energize relays 56, 57, 58, and 59, respectively, each having a normally opened contact 56a, 57a, 58a, and 59a, respectively. Each contact 56a, 57a, 58a, and 59a, respectively, forms a series circuit with a resistor 61, 62, 63, and 64, respectively. The series circuits are connected in parallel between a pair of resistance program treminals 66 and 67 of a resistance programmable current source 68, the output of which is connected to the coil 18 of the relay 10 through pins 22 and 27. The resistance programmable current source 68 and associated resistors and relays comprise the coil current waveform generator 31.

A resistance programmable current souce is a wellknown device in which the output of the current source is alterted by changing resistors connected between resistance program terminals to alter a resistance value in the current source circuit. The current source circuit is so arranged so that with no resistor externally connected between the resistance program terminals 66 and 67 zero current will flow in the coil 18. Conventional current or voltage programmable current sources would serve the same function as the resistance programmable current source 68.

The sequential energization of the relays 56, 57, 58, and 59, respectively, closes the normally opened contacts 56a, 57a, 58a, and 59a, sequentially, to sequentially connect the resistors 61, 62, 63, 64, respectively, between the resistance program terminals 66 and 67. The values of resistors 61, 62, 63, and 64 are each chosen so that the current flowing from the current source 68 through the coil 18 corresponds to the coil current waveform shown in solid lines in FIG. 5.

The current levels impressed in the coil 18 in response to connecting resistors 61, 62, 63, and 64 across the terminals 66 and 67 during the pulses P1 through P4, are designated nonoperate, coarse, hold, and coarse release, respectively. If the relay is properly adjusted and initially released, the increase in coil current from zero to the nonoperate level will not operate the relay; further increases in the coil current to the coarse operate level will operate the relay. Reducing the coil current of the now operated relay from the operate level to the hold level will not release the armature, but further reducing the coil current to the coarse release level will release the relay.

The detector unit 32 including four detect modules, designated nonoperate detect module 69, operate detect module 71, hold detect module 72, and release detect module 73, the details of which are shown in FIG. 5, is provided to sample the state of the relay 10 after each current level is applied to the coil 18, and store the information thus obtained. Sufficient time is allowed before the state of the relay is sampled for the armature 11 to respond to the current level applied. For purposes of convenience in this embodiment, the sampling of the armature 11 is initiated by the leading edge of the pulse succeeding the pulse initiating the respective current levels. The state of the relay can be sampled at this time even though the next current level is already impressed upon the coil 18 to again alter the state of the relay. The state of the relay can be sampled in several microseconds or less, however, due to mechanical inertia, the armature 11 cannot change or shift the state or even lift off the contact upon which is resting in a microsecond time interval.

Each detect module 69, 71, 72, and 73 (see FIG. 5) comprises a logic circuit including three NOR gates 74, 76, and 79, and two flip-flops 77 and 78. Each detect module has four input connections designated N.C., 1., T., and NO. and three output connections designated R., N., and W. The NC. input is directly connected to a first input of the NOR gate 74, while the NO. input is connected directly to a first input of the NOR gate 76. The 1. input is connected to a second input of each NOR gate 74 and 76, and the T. input is connected to a third input of each NOR gate 74 and 76. The NOR gates 74 and 76 will provide a ground level output unless each of the four respective inputs are grounded to provide an output of +V volts.

Referring now to FIGS. 2, 3, and 4, it is seen that the normally closed contact 12 of the relay 10 is connected through the pin 23 by lead 81 to the NC. input of each of the detect modules 69, 71, 72 and 73. The normally opened contact 13 of the relay 10 is connected through pin 26 by lead 82 to the NO. input of each of the detect modules 69, 71, 72, and 73. The armature 11 of the relay 10 is grounded through pin 24.

A pair of resistors 83 and 84 are internally connected in each detect module. The resistor 83 is connected between the NC. input and a voltage [V while the resistor 84 is connected between the NO. input, and a voltage +V. Therefore, when the armature 11 of the relay 10 is in contact with the normally closed contact 12, the voltage appearing at the NC. input of each detect module will be ground; while the input appearing at the NO. input of each detect module will be +V. In a like manner, when the armature 11 of the relay 10 is in contact with the normally opened contact 13, the N0. input of each detect module will be at ground; while the NC. input will be at +V.

The I. input of the nonoperate detect module 69 is electrically connected to ground. The I. input of the other detect modules 71, 72, and 73 are connected to the N. output of the preceding detect modules 69, 71, and 72, respectively. The T. input of each module 69, 71, 72, and 73 is connected to one of the output terminals T2, T3, T4, T5, respectively, of the sequential pulse generator 28.

The output of the NOR gate 74 is connected to a set input of the flip-flop 77. The output of the NOR gate 76 is connected to a set input of the flip-flop 78. The flip-flops 77 and 78 each have first outputs 86 and 87, respectively, normally at +V volts connected to the outputs R. and W., respectively, and second outputs 88 and 89, respectively, both connected to a pair of inputs of the NOR gate 79 and each connected to a fourth input of the NOR gates 76 and 74, respectively. An output of the NOR gate 79 is connected to the output terminal N.

Looking now at the nonoperate detect module 69, it is seen that the I. input is at ground, the T. input will be at ground only during the occurrence of the pulse P2 of the sequential pulse generator 28, and that only one of the inputs NO. and NC. can be at ground at any one time since the armature 11 can only be in contact with one of the contacts 12 or 13 unless the contacts 12 and 13 are shorted together. However, it is possible for the NC. and NO. input to both be at +V if the armature 11 sticks in a position between the two contacts. This situation is referred to in the relay art as hanging up. The fourth input of each NOR gate 74 and 76 will remain at ground until one of the flip-flops 77 or 78 is set.

Assume that the nonoperate current level generated in response to pulse P1 is insufilcient to operate the relay 10. Upon occurrence of the pulse P2, the input T. will be brought to ground, the NC. input of the detect module 69 will be grounded through the relay armature 11, and the ND. input will remain at 2+V. Therefore, it is seen that all the inputs of NOR gate 74 will be at ground providing an output to set the flip-flop 77. Setting of the flip-flop 77 will switch the output 88 to :+V, thereby disabling NOR gate 76 from operating even if during the time interval of pulse P2 the relay armature 11 operates to close the normally opened contact 13 and open the normally closed contact 12. Therefore, it is seen that the flip-flop 77 acts as both a storage device to store information indications of the state which the relay occupied in response to the first current level and also serve to lock out any additional information from being put into the detect module until the flip-flop 77 is reset by the first pulse P1 of the next adjusting sequence.

The output 86 of the flip-fiop77 provides a ground signal on the output terminal R., while the output 87 of the flip-flop 78 maintains a +V on the output terminal W. The +V level on the output 88 provides a signal to the NOR gate 79 to put a ground signal on the output terminal N., in this way enabling the succeeding detect module, such as modules 71 or 72 or 73, to be sampled by the succeeding pulse. It is readily apparent that if the armature 11 has operated in response to the applied current level, the flip-flop 78 would have been set so as to provide the ground level signal on the output terminal W. leaving a +V signal on the output terminal R. and disabling the NOR gate 74 from providing a set signal to the flip-flop 77. If the contacts 12 and 13 are shorted together, there is a possibility that both the flip-flops 77 and 78 will be set simultaneously, thereby providing +V levels on both the R. and W. outputs.

In a like manner, pulses P3, P4, and P render effective the operate detect module, hold detect module, and release detect module, respectively, to sample the state of the relay in response to the operate, hold, and release current levels generated. The I. input of the operate, hold,

and release detect modules are each connected to the N. output of the immediately preceding detect module; thus, if the relay armature 11 of the relay 10 under test does not contact one or the other of the contacts 12 and 13 during any one of the pulse periods P2, P3, P4, and P5, the succeeding detect modules are disabled from operation and the N. output of the release detect module 73 will remain at +V volts indicating a hung up relay. If the relay does not hang up during the current applying and relay state sampling interval, a ground output appears at the N. output of the release detect module 73, enabling the logic unit 33 to evaluate the information now stored in the detect modules 69, 71, 72, and 73.

The N. output of the release detect module 73 is inverted and the inverter output is gated through NOR gate 91 by the pulse P6 to a flip-flop 92. If the output of the release detect module 73 is at +V volts indicating a hung up relay, the flip-flop 92 changes state to provide +V output to an input of a reject NOR gate 93 providing a ground level at an output of the NOR gate 93 energizing a reject relay 94 having a normally opened contact 9411 in series with the light 42. Energization of the relay 94 closes normally opened contact 94a connecting the light 42 between a voltage -[V and ground, thereby lighting the light 42 indicating that relay 10 under test is not susceptible of adjustment.

The output N. of the release detect module 73 is provided as an input to an inhibit inverter 96, the output of which is connected to inhibit operation of other circuits in the logic unit 33 until the completion of the current applying and relay state sampling interval.

The R. output of the nonoperate detect module 69, the W. output of the hold detect module 72, and the output of the inhibit inverter 96 are applied to three inputs of an AND gate 97 to provide a +V signal to a second input of the reject NOR gate 93 when the relay 10 operates in response to the nonoperate current level and releases in response to the hold current level. The +V signal applied to the second input of the NOR gate 93 provides a ground level to the output of the NOR gate 93, energizing the relay 94 to light the light 42 and inhibiting further outputs from the logic unit 33.

When a relay 10 under test operates at a current level which is at a nonoperate level and releases at a current level which is at a hold level, subsequent demagnetization of the bias magnets 16 and 17 will not be able to bring the relay 10 into proper adjustment because demagnetiza tion of either of the bias magnets 16 or 17 will tend to adjust the actual nonoperate and hold current levels toward each other. To adjust such a relay, the actual nonoperate current level and the actual hold current level must be adjusted away from each other, that is the difference in current level needed (1) to operate and (2) the current level to hold must be increased.

When the relay 10 operates in response to the non operate current level or fails to release in response to the release current level the R. output of the nonoperate detect module 69 or the R. output of the release detect module 73 applies a +V signal to an input of an OR gate 98 to provide a =+V signal to a first input of a NAND gate 99. The output of the inhibit inverter 96 is connected to a second input of the NAND gate 99 so that upon completion of operation of the last detect module 73 a +V signal is applied to the NAND gate 99 from the inverter 96. The output of the reject NOR gate 93 is connected to a third input of NAND gate 99 so that a :+V level is applied to NAND gate 99 if a reject is not indicated. The three +V inputs to NAND gate 99 provide a ground level output to NAND gate 99, thereby energizing a relay 101 having three sets of contacts 101a, 10112, and 1010.

The energization of relay 101 switches contact 101a from a normally closed contact connected through a resistor 102 to a remote programable voltage source or facility 103 to a normally opened contact. The Switching of contact 101a connects a storage capacitor 104 initially charged by the voltage source 103 across the electromagnet 38 through the normally closed path of the relay 46, discharging the capacitor 104 so that an exponentially decaying sinusoid of current flows through the winding of the electromagnet 38. The period of the sinusoid is determined by the value of the capacitor 104 and the inductance of the electromagnet 38 while the exponential time constant of the decaying waveform is determined by the value of the capacitor 104, the inductance of the electromagnet 38, and the coil resistance of the electromagnet 38. A magnetic field results from the current flowing in the electromagnet 38 which demagnetizes the bias magnet 17 an amount proportional to the initial charge on the capacitor 104, thereby increasing (1)the current required to operate a released armature 11 and (2) the current at which an operated armature 11 will release.

Energization of relay 101 also closes contact 101b to apply a voltage input to a six stage binary counter 106 to advance the counter 106 one count. The output of the binary counter 106 is fed into a digital-to-analog converter 107 which converts the count stored in the counter to an analog voltage having an amplitude proportional to the stored count. This voltage is applied to the remote programable voltage source 103 to alter the output voltage of the voltage source 103 by a proportional amount. It should be understood that a resistance, conductance, or current programable voltage source could be substituted for the voltage programable voltage source 103, in which case, the digital-to-analog converted 107 would provide a resistance, conductance, or current output. The six stage counter 106 is set to an initial count so that an initial charging voltage appears at the output of the voltage source 103.

The voltage source 103 applies the initial low voltage to the capacitor 104 through the resistor 102. The time constant of the resistor 102-capacitor 104 network is such that the capacitor 104 will charge to the output voltage of the voltage source 103 in approximately forty milliseconds, but will not appreciably change the voltage across the capacitor 104 should contact 101b 'close a few microseconds before contact 101a switches. The stepping of the counter 106 therefore increases the voltage output of the voltage source 103 when the contact 10111 closes, but does not-increase the voltage across the capacitor 104 until the next adjusting sequence. If it were desired to charge the capacitor 104 in the same adjusting sequence as the capacitor 104 is discharged through the electromagnet 38, not only would more involved switching be necessary, but a voltage source having a higher current capability than the voltage source 103 would be required to charge the capacitor 104 in a shorter period of time. By setting the voltage source 103 to an initial voltage, the bias magnet 17 can be demagnetized a fixed increment during the first adjusting sequence, thus decreasing the total adjusting time.

Further, the energization of relay 101 closes normally opened contact 1010 to connect a light 39 between +V and ground, thereby illuminating the light 39 to give a visual indication of partial demagnetization of the bias magnet 17. It may be appreciated that the capacitor 104, the remote programable voltage source 103, the digitalto-analog converter 107, the six stage binary counter 106, the relay 101, and a two stage binary counter 108 all cooperate to function as the bias magnet demagnetization unit 36, shown in FIG. 1.

When the relay does not operate in response to the operate current level or releases in response to the hold current level, the W. output of the operate detect module 71 or the W. output of the hold detect module 72 applies +V signal to one of the two inputs of an OR gate 109 to provide a +V signal to a first input of a NAND gate 111. Upon completion of operation of the last detect module 73, the output of the inverter OR gate 96 applies a +V signal to a second input of the NAND gate 111.

10 If no reject is indicated, NOR gate 93 provides a +V signal to a third input of NAND gate 111. If demagnetization of bias magnet 17 is not required, NAND gate 99 provides +V signal to a fourth input so that a ground level signal is provided at the output of the NAND gate 111, thereby energizing a relay 112 having three sets of contacts 112a, 112b, and 1120.

The second bias magnet demagnetization unit 34, the relay 112, a capacitor 113, a resistor 105, a remote programable voltage source 114, a digital-to-analog converter 116, a six stage binary counter 117, and a two stage binary counter 118 comprise the contacts of the relay 112 connected in the bias magnet demagnetization unit 34 and operate in the same manner as the relay 101 operates in the bias magnet demagnetization unit 36.

The energization of relay 112 switches contact 112a from a normally closed contact connected through a resistor 105 to a remote programable voltage source 114 to a normally opened contact. The switching of contact 112a connects a storage capacitor 113 initially -charged by the voltage source 114 across the electromagnet 37 through the normally closed path of the relay 46, discharging the capacitor 113 so that an exponentially decaying sinusoid of current floWs through the winding of the electromagnet 37. The period of the sinusoid is determined by the value of the capacitor 113 and the inductance of the electromagnet 37, while the exponential time constant of the decaying waveform is determined by the value of the capacitor 113, the inductance of the electromagnet 38, and the coil resistance of the electromagnet 37. A magnetic field results from the current flowing in the electromagnet 37 which demagnetizes the bias magnet 16 an amount proportional to the initial charge on the capacitor 113, thereby increasing (1) the current required to operate a released armature 11 and (2) the current at which an operated armature 11 will release.

Energization of relay 112 also closes contact 11211 to apply a voltage input to a six stage binary counter 117 to advance the counter 117 one count. The output of the binary counter 118 is fed into a digital-to-analog converter 116 which converts the count stored in the counter to an analog voltage having an amplitude proportional to the stored count.

Operation of the bias magnet demagnetization unit 34 decreases (1) the current required to operate a released armature 11 and (2) the current at which an operated armature 11 will release.

After the completion of operation of the last detect module 73 if a reject is not indicated and if demagnetization is not indicated and the relay 10 (1) does not operate in response to the nonoperate current level, 2) operates in response to the operate current level, (3) holds in response to the hold current level and (4) releases in response to the release current level, the W. output of the nonoperate detect module 69, the R. output of the operate detect module 71, the R. output of the hold detect module 72, and the W. output of the release detect module 73 each apply a +V signal to one of four inputs of a NAND gate 119 to provide a ground level output signal. The ground level is inverted to set a flip-flop 122 and energize a relay 121 having a normally opened contact 121a. The energization of the relay 121 closes normally opened contact 121a to connect the light 43 between +V and ground to indicate a properly adjusted relay.

If the contacts 12 and 13 are shorted together to provide +V outputs on both the R. and W. outputs of the detect modules 69, 71, 72, and 73, it is desirable that a properly adjusted relay is not indicated. Therefore, inhibit signals are applied from NOR gate 93 to (1) the NAND gates 99 and 111 and (2) the NAND gate 119 to prevent a properly adjusted relay from being indicated when, in fact, the relay under test is defective.

Setting of the flip-flop 122 provides a +V output signal which energizes a relay 123 having four sets of contacts 123a, 123b, 1230, and 123d. Energization of the relay 123 switches contacts 123a and 123b, associated with sequential pulse generator 28, from a normally opened state to a normally closed state, disconnecting relays 57 and 69 from the terminals T2 and T4 of the sequential pulse generator 28 and connecting relays 124 and 126 to the terminals T2 and T4, respectively, and switches the contacts 1230 and 123d from a normally opened to a normally closed state, disconnecting contacts 101b and 11212 from the input of the six stage binary counters 106 and 117, respectively, and connecting the contacts 101b and 112k to the input of the two stage binary counters 108 and 118, respectively. A most significant or last digit output of the two stage counters 108 and 118 is provided to drive the six stage counter-s 106 and 117.

The coil current waveform generator 31 is switched to fine when relays 124 and 126 have normally opened contacts 124a and 126a forming series circuits with resistors 127 and 128, respectively. The series circuits are connected in parallel across the resistance program terminals 66 and 67. The values of the resistors 127 and 128 are chosen so that upon the occurrence of succeeding adjusting sequences, the operate current level of the coil current waveform is reduced and the release current level of the coil current waveform is increased, as shown in- FIG. 4 by the dashed lines. Now with the two stage binary counters 108 and 118 in series with the six stage binary counters 106 and 117, respectively, each time an input is applied by actuation of the contacts 101b and 112b the voltage of the remote programable voltage sources 103 and 114 are changed by smaller increments than if the contacts 101b and 11212 directly actuated the six stage binary counters 106 and 117.

During the next adjusting sequence, the relay adjusting set operates as previously described except that (l) the values of the operate current level of the coil current waveform is reduced and the release current level of the coil current waveform is increased, thereby requiring the relay to be adjusted to a more stringent tolerance, and (2) the increments of the demagnetization of the bias magnets 16 and 17 are reduced to enable the relay 10 to be adjusted to the more stringent tolerance.

In summary, referring again to FIG. 2, it may be appreciated that a relay to be adjusted by the system described is first subjected to the pair of saturating magnetic fields to fully saturate the bias magnets 16 and 17. Next, the coil current waveform is applied to the coil 18, the response thereto sampled and stored in the detect module 32. The information stored in the detect module 32 is evaluated in the logic unit 33. If the information indicates as unadjustable relay, the relay 94 (see FIG. 3) is closed, lighting the reject light 42. It is apparent that the relay 94 could have any number of contacts with which any number of indicators could be actuated, one contact could be used to terminate operation of the sequential pulse generator 28. In this particular embodiment, however, the sequential pulse generator 28 continuously cycles so that even if a reject is indicated, a second coil current waveform is applied to the coil 18 and another adjusting sequence proceeds.

If evaluation indicates that either of the bias magnets 16 or 17 requires demagnetization, such action is initiated. If an acceptable relay is indicated, the relay adjusting set is switched from coarse to fine adjusting and again another adjusting sequence is commenced. It is possible that one can satisfactorily adjust a relay set without the coarse and fine control. However, using both the coarse and fine controls there is an increase in both the speed and accuracy with which relays may be adjusted. It should also be apparent that the signal from the logic unit 33 indicating an acceptable relay also could be used to terminate operation of the sequential pulse generator 28 or eject the relay from the adjusting set. However, in this par ticular embodiment, a properly adjusted relay or a rejected relay is indicated when the lights 42 and 43 continuously light on a series of succeeding adjusting sequences. When a relay is removed from the adjusting set and a new relay is placed therein for adjustment, a switch 129 having four contacts 129a, 1291), 1290, and 129d is depressedto reset the flip-flops 54 and 122 and the binary counters 117, 118, 106, and 108 so that the first series of pulses from the sequential pulse generator 28 saturates the bias magnets 16 and 17 of the new relay and the first adjusting sequence will begin thereafter with the relay adjusting set in the coarse adjusting condition.

What is claimed is:

1. In a system for adjusting an operating characteristic of a relay having a coil and an armature biased by a first and second permanent magnet;

an inductive coil for applying a demagnetizing force to said first permanent magnet;

a repetitively operated sequential pulse generator for generating successive control pulses;

means operated by a predetermined plurality of said control pulses for applying a current waveform comprised of four predetermined steps to said relay coil to operate said armature in accordance with a desired characteristic;

a normally nonoperated counting circuit responsive to an operating signal for providing digital outputs;

a digital-to-analog converter connected to and operated by said counting circuit for producing analog voltage outputs of successively larger magnitudes;

means responsive to said operating signal for energizing said inductive coil to demagnetize said first permanent magnet an increment proportional to said analog voltage;

a gating circuit for providing said operating signal;

first detection means responsive to each failure of said armature to function in accordance with the desired characteristic and in response to two of said steps applied to said relay coil for conditioning said gating circuit to operate;

a second means for applying a demagnetizing force to said second permanent magnet;

a second normally nonoperated counting circuit responsive to a second operating signal for energizing said second demagnetizing means to incrementally demagnetize said second permanent magnet;

a second gating circuit for providing said second operating signal;

second detection means responsive to each failure of said armature to function in accordance with the desired characteristic and in response to two of said steps applied to said relay coil for conditioning said second gating circuit to operate; and

means for applying one of said succeeding control pulses after said predetermined plurality of control pulses to operate at least one of said conditioned gating circuits.

2. In a system for demagnetizing a saturated bias magnet positioned to control an armature of a relay:

means for applying a demagnetizing field to said bias magnet;

a power supply facility having a control means for varying an output voltage from said facility;

a digital-to-analog converter for applying a signal to said control means to accordingly vary the output of said power supply facility;

a first multistage counter circuit for applying digital signals to said converter upon operation of each stage;

means for periodically applying first operate signals of a first predetermined magnitude to said relay to operate said armature;

first switching means responsive to the failure of said armature to operate in response to said first operate signal for pulsing said first counter circuit to operate said converter and said control means in said power supply facility;

means also responsive to the failure of said armature to operate in response to said first operate signal for applying the output of said power supply facility to said demagnetizing means;

a second multistage counter circuit for applying digital signals to said converter upon operation of'each stage;

means for applying the output of the last stage of said second counting circuit to drive said first counting circuit;

a second normally unoperated switching means responsive to the operation of the armature in response to said first operate signal for connecting said first switching means to said second counter circuit and for disconnecting said first first counter circuit from said first switching means;

means also responsive to the operation of the armature in response to a first operate signal for applying second operate signals of a second predetermined magnitude to said relay to operate said armature; and

means responsive to the failure of said relay to operate said armature in response to a second operate signal for operating said first and second switching'means to successively apply the output of said first and second counting circuits to said converter whereupon the output from said power supply facility is-varied in applying a demagnetizing field to said bias magnet.

3. In a system for controlling the demagnetization of a bias magnet associated with an armature of a relay:

a coil for applying a demagnetizing field to said bias magnet;

a power supply means;

a capacitor;

a movable contactor for selectively connecting the capacitor to said power supply means and then said coil;

a first multistage counting means for controlling the output of said power supply means in accordance with the stage of operation of said counting means to control the charging of said capacitor;

a second multistage counting means for controlling the output of said power supply means in accordance with the stage of operation of said second counting means to control the charging of the capacitor;

means operated by the operation of the last stage of said second counting means for successively driving said first counting means;

means for generating a series of first operate pulses of a first predetermined magnitude and then a series of second operate pulses of a second predetermined magnitude;

means for applying sequentially said operate pulses to said relay to operate said armature;

means responsive to the failure of said armature to operate upon application of said first operate pulses for operating said first counting means and for moving said contactor to connect said capacitor to said coil to demagnetize said bias magnet; and

means responsive to the failure of said armature to operate upon application of said second operate pulses for operating said second counting means and for moving said contactor to connect said capacitor to said coil to demagnetize said bias magnet.

References Cited UNITED STATES PATENTS RUDOLPH V. ROLINEC, Primary Examiner US. 01. X.R, 

